1. Field of the Invention
The present invention relates to a power control system and a power amplification system using the same, and more particularly, to a power control system that can control a power current on the basis of currents flowing through a plurality of predetermined PMOS transistors among a plurality of power PMOS transistors included in a power regulator, and a power amplification system using the same.
2. Description of the Related Art
With advancements in mobile communications technologies, the demand for power amplifiers, which are used to amplify the output of RF signals in RF terminals of mobile communications terminals, has exploded in recent years. In particular, research has been actively conducted into power amplifiers using CMOS technology for integration and reduction in size, weight, and thickness. In particular, power regulators (LDO: low-dropout) have been developed for power amplifiers so as to stably control the operation of the power amplifiers. Also, research and development efforts focused on providing more stable voltage by using these power regulators (LDO) have been made.
In the related art, a power regulator (LDO) includes a plurality of power PMOS transistors connected in parallel with each other in order to provide currents required by a power amplifier.
The plurality of PMOS transistors respectively supply predetermined amounts of currents. The currents, supplied by the respective PMOS transistors, are totaled to thereby supply the currents required by the power amplifier.
FIG. 1 is a block diagram illustrating a power amplification system according to the related art.
Referring to FIG. 1, a power amplification system using a power regulator according to the related art includes a power regulator 10 and a power amplifier 20 connected to a battery voltage source Vbat in parallel with each other. The power regulator 10 supplies a current Id and a voltage Vd, which are controlled according to a lamp voltage Vramp being input. The power amplifier 20 has a power transistor MOS that receives the voltage and the current from the power regulator 20 to thereby amplify the power of a signal Rfin being input.
Here, a single sensing PMOS transistor that senses a current flowing through a single specific PMOS transistor among a plurality of power PMOS transistors, included in the power regulator 10, is connected in order to accurately control the current being supplied from the power regulator 10.
The current, sensed by the sensing PMOS transistor, is converted into a voltage, and a bias current of the power amplifier is controlled on the basis of a voltage difference between the voltage and a reference voltage.
In the power control system according to the related art, a power regulator includes a plurality of power PMOS transistors. Since the plurality of power PMOS transistors operate at a low source-drain voltage, the power regulator operates even in triode regions where even a small change in a drain current may cause a big change in current. Therefore, under these operating conditions, current control needs to be performed.
In this power control system according to the related art, a current flowing through a single specific PMOS transistor of the power regulator is sensed and converted into a voltage, and a bias current of the power amplifier needs to be controlled according to a voltage difference between the voltage and a reference voltage.
However, the power control system according to the related art, metal lines present between the plurality of power PMOS transistors, included in the power regulator, create different impedances between the plurality of power PMOS transistors due to which, precise control of the electric current may not be achieved.